White matter protection by inhibitors of glial scar formation in perinatal hypoxia ischemia

项目摘要 早产幸存者通常被诊断为持续性脑白质损伤(WMI)，导致 正常髓鞘形成失败。髓鞘形成障碍会导致终生运动和神经行为障碍。这个 WMI的中心特征是所谓的“胶质疤痕”，这是一种由反应性星形胶质细胞产生的抑制性屏障，它 通过阻断少突胶质细胞前体细胞的成熟而导致髓鞘形成失败。这是我们的长期目标 目的探讨通过预防胶质瘢痕形成来预防髓鞘衰竭的新疗法。 在弥漫性反应性星形胶质细胞增生症之前，没有预防早期形成的治疗策略。 慢性阻止髓鞘形成。 WMI破坏了细胞外基质透明质酸(HA)主干的完整性。我们已经定义了一个 小分子~5 kDa HA寡聚体(HA5)调控星形胶质细胞增殖的新途径 并促进反应性星形胶质细胞增生症。通过酶肿瘤 坏死性 因数- (肿瘤坏死因子) 受刺激 基因-6(TSG-6)，HA5作为一个汇，捕获间α-抑制物的重链(HC)蛋白亚基 蛋白质(II)复合体。这个反应产生不稳定的中间产物II，释放HC。我们有 确定了新的方法来阻断这种TSG-6依赖的途径，以显著减弱 神经胶质疤痕。我们的压倒一切的假设是HA5介导的HC释放促进反应性星形胶质细胞增生 通过src家族依赖的激酶途径。我们提出了三个具体目标来检验这一假设。在AIM 1、我们假设胶质瘢痕中透明质酸酶的激活促进了HA5的形成。我们会 确定产生HA5以促进胶质瘢痕形成的透明质酸酶(HYAL)，并确定 广谱HYAL抑制剂可减少WMI引起的星形胶质细胞增生症。在目标2中，我们将测试 HA5通过依赖TSG-6促进星形胶质细胞增殖和反应性星形胶质细胞增生症的假说 II来源的重链的释放我们将确定WMI中星形胶质细胞的增殖是否依赖于 在体外和体内通过HC依赖机制促进星形胶质细胞增生的TSG-6的表达。在《目标3》中， 我们推测，TSG-6的激活通过激活src家族激酶来介导神经胶质瘢痕的形成。我们 将首先确定TSG-6阻断抗体是否在体内抑制星形胶质细胞前体细胞的增殖。我们会 测试一种目前处于临床试验中的src激酶抑制剂，作为一种阻止胶质瘢痕形成和 促进髓鞘形成。在这些研究的结论中，我们希望定义新的治疗策略来 在WMI早期进行干预，以防止胶质瘢痕的形成并促进髓鞘形成。考虑到这种反应性 星形胶质细胞增多症是许多形式的中枢神经系统损伤的中心特征，我们的发现可能对其他 儿童和成人神经疾病与突出的WMI。

Project Summary Survivors of preterm birth are commonly diagnosed with persistent white matter injury (WMI) that leads to a failure of normal myelination. Myelination failure results in life long motor and neurobehavioral disabilities. The central feature of WMI is the so-called “glial scar,” an inhibitory barrier generated by reactive astrocytes, which causes myelination failure by blocking the maturation of oligodendrocyte progenitors. It is our long-term objective to develop novel therapies to prevent myelination failure by preventing glial scar formation. There are no therapeutic strategies to prevent early formation of diffuse reactive astrogliosis before it chronically blocks myelination. WMI disrupts the integrity of the hyaluronic acid (HA) backbone of the extracellular matrix. We have defined a novel pathway through which small ~5 kDa HA oligomers (HA5) regulate the proliferation of astroglial progenitors and promote reactive astrogliosis. Through the enzyme tumor necrosis factor- (TNF) stimulated gene-6 (TSG-6), HA5 serves as a sink that traps heavy chain (HC) protein subunits of the inter-alpha-inhibitor protein (II) complex. This reaction generates unstable intermediates of II that release HC. We have identified novel approaches to block this TSG-6-dependent pathway to markedly attenuate the formation of the glial scar. Our over-riding hypothesis is that HA5-mediated HC release promotes reactive astrogliosis via a src family kinase-dependent pathway. We propose three specific aims to test this hypothesis. In aim 1, we hypothesize that hyaluronidase activation in the glial scar promotes the formation of HA5. We will determine the hyaluronidases (HYAL) that generate HA5 to promote formation of the glial scar and determine if a broad spectrum HYAL inhibitor reduces astrogliosis in response to WMI. In aim 2, we will test the hypothesis that HA5 promotes astrocyte proliferation and reactive astrogliosis through TSG-6-dependent release of heavy chains derived from II. We will determine if astrocyte proliferation in WMI is dependent on TSG-6 expression that promotes astrogliosis in vitro and in vivo via an HC-dependent mechanism. In aim 3, we hypothesize that activation of TSG-6 mediates glial scar formation via activation of src family kinases. We will first determine if a TSG-6 blocking antibody inhibits proliferation of astrocyte progenitors in vivo. We will test a src kinase inhibitor, currently in clinical trials, as a novel strategy to block glial scar formation and promote myelination. At the conclusion of these studies, we expect to define new therapeutic strategies to intervene during early WMI to prevent formation of the glial scar and promote myelination. Given that reactive astrogliosis is a central feature of many forms of CNS injury, our findings may have potential benefit for other pediatric and adult neurological disorders with prominent WMI.